This invention relates to a printing device and a printing method and, more particularly, to a printing device and a printing method for printing prescribed information on such image receiving media as bank cards, ID cards, booklets, passbooks and so forth.
A printing device that is capable of making a high quality printing without affected by the surface conditions of image receiving media such as cards, passbooks and other media to the extent possible is demanded in recent years. As one of this type of printing devices, a printing device to use an intermediate transfer ribbon as an intermediate transfer ribbon is well known. This type of printing device comprises a printer portion and a transferring portion. The printer portion has a thermal print head and an ink ribbon. The transferring portion has a heat roller and a back-up roller.
The intermediate transfer ribbon is supplied into the printer portion. In this printer portion, the thermal print head is heated according to prescribed information and an ink of the ink ribbon is melted and prints prescribed information such as characters, bar codes, etc. on the surface of an intermediate transfer ribbon.
The intermediate transfer ribbon with prescribed information printed is supplied between the heat roller and the back-up roller in the transferring portion. At this time, an image receiving medium with its transfer surface arranged to face the intermediate transfer ribbon is simultaneously fed between the heat roller and the back-up roller.
The heat roller is rotated in this state and the intermediate transfer ribbon and an image receiving medium are pushed against the back-up roller and heated, and prescribed information is transferred on the surface of the image receiving medium. The intermediate transfer ribbon comprises a long base film and a transferring layer coated on this base film. In the transferring portion, the transferring layer is transferred on an image receiving medium together with the prescribed information printed on the transferring layer.
On the transferring layer or an image receiving medium, prescribed information that are optically read may be printed sometimes. On the other hand, in order for preventing forgery of peculiar prescribed information on an image receiving medium, a protection film given with a transparent hologram in a specified pattern may be coated over an image receiving medium. The printing device described above is capable of printing prescribed information on an image receiving medium and coating a surface protection film at the same time.
Even when image receiving media are in the same kind but different in thickness, a spring force to push down the back-up roller during the transferring is changed by a difference in thickness of image receiving media. This means that the pressure at the time of transfer varies depending on a thickness of an image receiving medium. When the pressure at the time of transfer is changed depending upon an image receiving medium, improper conveyance of an image receiving medium or an intermediate transfer ribbon and improper transfer of prescribed information on an image receiving medium may result.
Further, even in the same book-shaped image receiving medium, if an opened page (a transferring page) differs, the thickness of the medium is varied and accordingly, the pressure (a contracting amount of a spring) at the time of transfer changes and the improper conveyance or improper transfer may result.
Further, when transferring information on an open page of the same book-shaped image receiving medium, a swelling (slackening) may be generated on the seam of the page. When information is transferred under this state, the surface of an image receiving medium may contact the intermediate transfer ribbon, and the protection film of the intermediate transfer ribbon may adhere to the outside of the transfer area of an image receiving medium, for example, the seam area of the page where the swelling is easily generated and the defective transfer may result.
Further, in recent years, bank cards and passbooks may have IC, etc. embedded in many cases and the uneven surfaces of them may cause improper printing when melting and printing information on the surfaces. In addition, when making the printing of high quality images on passbooks, minute uneven surfaces resulted from paper fibers caused deterioration of image quality.
So, a printing technology that is not affected by the surface conditions of card and passbooks as could as possible is demanded and one of this technology, a printing using such the intermediate transfer ribbon as described above is known.
The intermediate transfer ribbon comprises a long base film and a transferring layer coated on this base film. When an image is transferred on an image receiving medium in the transferring portion, the transferring layer is separated and an image is transferred on an image receiving medium together with the transferring layer.
However, when separating the intermediate transfer ribbon and an image receiving medium that are heated and press fitted between the heat roller and the back-up roller at the time of image transfer, if the stiffness of an image receiving medium was weak, the transferring layer with an image printed was not separated satisfactorily from the base film and an image receiving medium was pulled by the intermediate transfer ribbon in the state kept adhered to the transferring layer or an image receiving medium itself was broken. Therefore, there were such problems that it was necessary to use image receiving media made of relatively strong material and the degree of freedom for selection of image receiving media was low and cost increased.